The invention relates to a workstation having multiple robots and multiple fixtures, and more specifically, the invention provides welding workstations for automotive assembly lines having multiple independently-working welding robots and multiple fixtures for holding workpieces.
The efficiency of a welding workstation can be defined by the amount of time, normally a percentage, that a welding robot spends welding compared to the total time required for a particular repetitive cycle. The efficiency of the workstation relates to the amount of time that a welding robot takes to perform various welding operations compared to the total amount of time that the welding robot requires for a particular repetitive cycle. Idle time for a welding robot can occur when a new workpiece is loaded and prepared in a fixture. If the workstation has one welding robot and one fixture, the welding robot will stand idle as a completed part is unloaded from the fixture and a new workpiece is loaded onto the fixture. In the prior art, this problem was addressed by adding a second fixture at the workstation within reach of a single welding robot. In a workstation with two fixtures, the welding robot can complete welding operations at one fixture while workpieces are being loaded and unloaded at the second fixture. When the welding process is complete at the first fixture, the welding robot can move to the second fixture and immediately commence welding.
The amount of time that a workpiece is positioned in a fixture while work is being performed compared to the total amount of time that a workpiece is positioned in a fixture corresponds to workpiece efficiency. The amount of time that a workpiece sits idle in a fixture reduces the overall operating capacity of the workstation by reducing throughput, normally reported in parts per hour or similar units for the overall assembly process. In a workstation having one fixture and one welding robot, the amount of time that a workpiece sits idle in the fixture is minimized because the welding robot immediately commences welding operations as soon as a workpiece is loaded and any other setup procedures are completed. However, in a workstation that has two fixtures and one welding robot, a workpiece is loaded onto one fixture, is setup, and then sits idle until the welding robot completes welding operations at the second fixture. Therefore, in a workstation having one fixture and one welding robot, the workpiece efficiency is maximized while in a workstation having two fixtures and one welding robot the welding efficiency is maximized. It is desirable to provide a workstation wherein the welding efficiency and the workpiece efficiency are both enhanced.
The present invention includes a workstation having multiple robots and multiple fixtures. The workstation can perform processing operations on multiple workpieces sequentially or simultaneously. The robots performing processing operations on the workpieces are disposed between the fixtures and are independently movable relative to each other. The fixtures can be rotatable about a horizontal axis to position one of two or four major surfaces in a ready position for receiving workpieces. Each major surface has a separate workpiece rest for receiving workpieces of different configurations.
The present invention also includes a plurality of similar workstations positioned in sequence along an assembly line. A transfer robot can be disposed in between adjacent workstations for moving workpieces from one workstation to the next. The present invention can also include a robot for processing the workpieces while held by the transfer robot in between the adjacent workstations.
The present invention also provides an electronic control means for coordinating the movements of the processing robots. The electronic control means is programmable for processing any mix of workpieces of different configurations in any sequential order. The electronic control means presents the appropriate workpiece nest in the ready position to receive the workpiece to be processed next and operates the plurality of robots in programmable sequence to perform the necessary welding in an efficient manner for the particular workpiece.